Chairs with adjustable backrests are well known. Such prior art chairs typically allow the backrest to recline, rise and lower, and the lumbar support to be adjusted. These adjustments are typically enabled by mechanical devices. While such devices permit the backrest to be adjusted in a particular position, the backrest is then locked in the selected position, or its movement is restricted along one or more axes.
Recent research has suggested that it may be beneficial to the musculoskeletal system of a user to continually move while seated. Accordingly, there is a need for an improved chair which encourages the user to continually move, while at the same time providing continuous support by permitting the backrest to move with the user in multiple degrees of freedom.